Trying To Identify Extra Pipes Into Boiler

[plumbandplumber]

I have a fully pumped s-plan vented system, with hot water cyl. and 6 rads. I'm trying to understand the layout and am confused about two extra pipes that go into the top of the boiler - a Thorn Olympic.

There are 5 pipes in total, as follows -

15mm gas pipe to bottom of boiler
28mm flow to top of boiler
28mm return to top of boiler
15mm pipe to top of boiler - ?
22mm pipe to top of boiler - ?

Can anyone tell me what the last 2 pipes may be for? It's hard to identify them, as all the pipes run away from the boiler at head height along the wall before vanishing upstairs in the floor to rads and then loft tanks 2 floors up. Some of the pipes run in voids in walls. The only thing that's on the ground floor near the boiler is the hot water cylinder.

Thanks for any help.

 

[ShaunCorbs]

Fill (15mm) and vent (22mm) at a guess

 

[plumbandplumber]

Fill (15mm) and vent (22mm) at a guess

Yes, that would make sense. I was wondering where these entered the system as it's impossible to trace their routes down 2 floors from the loft tanks. As said, the pipes run through floors and voids before they all emerge together near cylinder and run along wall to boiler. The pump is on the 28mm return close to the boiler.

I've only ever seen feed and vent pipes tee'd into pipes before. So it's possible in my case they go direct into boiler?

Thanks for your help.

 

[ShaunCorbs]

Yes normally found on old school boilers

 

[plumbandplumber]

Yes, definitely old school and a bit heavier on the gas, but just keeps going and going. Only 6 rads and a cylinder so not exactly breaking the bank. Wouldn't swap it unless I really had to.

Thanks again for solving the mystery.

 

[Chalked]

As Shaun says the other two are feed and vent. It's a shame on open vented that we went to 2 connections. This way of piping up, makes sure that it won't pump over, or pull in air. Bet the system is as clean as a whistle too

 

[plumbandplumber]

Thanks. The water's not too bad judging by the last drain down. Do get small amount of air in bathroom rad, but all others ok. Only needs bleeding couple of times a year. Boiler kettles slightly, but I'm going to put some silencer in and see if it improves. Not too worried as you would need to stand right next to it to hear it.

Boiler seems to emit a lot of heat through casing compared to new boilers. Certainly don't need a rad in the same room as boiler. 🙂

 

[ShaunCorbs]

I wouldn't put anything in it,

I would say your running a gravity hot water setup so it might make a noise or two

 

[plumbandplumber]

No I believe it's fully pumped, because the boiler and cylinder are both on the ground floor. The cylinder is actually slightly lower than the boiler.

Another question - with the feed pipe being joined directly to the boiler, does it mean it's less likely to get than feed pipes that are tee'd into pipework elsewhere?

 

[ShaunCorbs]

there should be two pumps then one on the 28mm and one on the 22mm